To understand the role of attention, it is important to know the answer to the following question: what processing can occur without attention? This has not been adequately answered, which may be one reason researchers are still far from understanding how attention affects processing. The experiments proposed here will use psychophysical adaptation and fMRI to assess the processing of completely unattended stimuli. The stimuli will be completely unattended because they will be "crowded". In crowded displays, stimuli which are presented in the periphery between similar items cannot be attended or perceived despite extended viewing time. These experiments will yield significant knowledge of the processing of unattended stimuli in the case of crowding. Crowding may then be used as a tool to investigate other attentional issues, such as the difference between exogenous and endogenous cuing.